"When shopping at salvage grocery stores, it is more of a quality issue versus a safety issue," said nutritionist Rania Batayneh, MPH. "The reason being is that The Food and Drug Administration approves of outdated fare! The government agency determines that expiration dates are simply an indication of optimum quality as deemed by the manufacturer."

This can make it difficult to wrap your head around what's OK to eat and what you'd better pass up. To help you make the most of your trip—and save BIG—we tapped Batayneh (and the trusty old Internet) for some helpful tips.

Use-by, expired by and sell by all mean different things. "Use by" or "best if used by" refers to the flavor and quality of the food, not its safety. Use this label as a guideline to eat the food by its peak quality. To optimize its flavor, freeze the food at peak quality sooner rather than later to retain its color, nutrients and texture, says the U.S. Department of Agriculture.

"Sell by" tells the store how long to display the item. "Expiration date" doesn't refer to food safety, but rather how long the food can be used at peak quality.

"If foods are handled and stored properly, they can remain safe to consume well after the sell-by date," said Batayneh.

Practice safe storage. Fresh produce and refrigerated foods should be stored below 41 degrees Fahrenheit, Batayneh said. Canned foods and shelf-stable goods like salad dressings, can be consumed for years beyond their expiration date, but we wouldn't recommend keeping these for more than a year as they start to lose nutrients and the metal lids can rust. Store cans at 75 degrees Fahrenheit in your pantry, and discard them after the date (if they have one).

Go for non-perishable, boxed items like pasta, cake mix and granola bars. "These are just fine," said Batayneh.If stored in a dry, cool place they'll stay tasty for up to six months, except for cereal, which starts to taste stale about a month after being opened.

Skip the meat and cold cuts. Sounds obvious, but it might not look that way. "Meats pose a threat," Batayneh said, as they should be bought (and cooked) well before the sell-by date and eaten within a day or two of purchase, according to Consumer Reports. If the meat stinks or its colors have gone gray or green, toss it.

As for cold cuts, listeria, E. coli and Salmonella—headline-makers that can be fatal in young children and the elderly, according to the Centers for Disease Control—are reasons enough to keep these out of your cart.

Stock up on canned tuna. "Provided it's been stored properly and the unopened can isn't damaged," said Batayneh, just approach it as if it were soup and steer clear of rusty cans.